Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2232 insertions, 0 deletions

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
new file mode 100644
index 0000000000..2d14b0d785
--- /dev/null
+++ b/drivers/net/usb/usbnet.c
@@ -0,0 +1,2232 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * USB Network driver infrastructure
+ * Copyright (C) 2000-2005 by David Brownell
+ * Copyright (C) 2003-2005 David Hollis <dhollis@davehollis.com>
+ */
+
+/*
+ * This is a generic "USB networking" framework that works with several
+ * kinds of full and high speed networking devices:  host-to-host cables,
+ * smart usb peripherals, and actual Ethernet adapters.
+ *
+ * These devices usually differ in terms of control protocols (if they
+ * even have one!) and sometimes they define new framing to wrap or batch
+ * Ethernet packets.  Otherwise, they talk to USB pretty much the same,
+ * so interface (un)binding, endpoint I/O queues, fault handling, and other
+ * issues can usefully be addressed by this framework.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/ctype.h>
+#include <linux/ethtool.h>
+#include <linux/workqueue.h>
+#include <linux/mii.h>
+#include <linux/usb.h>
+#include <linux/usb/usbnet.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/pm_runtime.h>
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * Nineteen USB 1.1 max size bulk transactions per frame (ms), max.
+ * Several dozen bytes of IPv4 data can fit in two such transactions.
+ * One maximum size Ethernet packet takes twenty four of them.
+ * For high speed, each frame comfortably fits almost 36 max size
+ * Ethernet packets (so queues should be bigger).
+ *
+ * The goal is to let the USB host controller be busy for 5msec or
+ * more before an irq is required, under load.  Jumbograms change
+ * the equation.
+ */
+#define	MAX_QUEUE_MEMORY	(60 * 1518)
+#define	RX_QLEN(dev)		((dev)->rx_qlen)
+#define	TX_QLEN(dev)		((dev)->tx_qlen)
+
+// reawaken network queue this soon after stopping; else watchdog barks
+#define TX_TIMEOUT_JIFFIES	(5*HZ)
+
+/* throttle rx/tx briefly after some faults, so hub_wq might disconnect()
+ * us (it polls at HZ/4 usually) before we report too many false errors.
+ */
+#define THROTTLE_JIFFIES	(HZ/8)
+
+// between wakeups
+#define UNLINK_TIMEOUT_MS	3
+
+/*-------------------------------------------------------------------------*/
+
+// randomly generated ethernet address
+static u8	node_id [ETH_ALEN];
+
+/* use ethtool to change the level for any given device */
+static int msg_level = -1;
+module_param (msg_level, int, 0);
+MODULE_PARM_DESC (msg_level, "Override default message level");
+
+/*-------------------------------------------------------------------------*/
+
+static const char * const usbnet_event_names[] = {
+	[EVENT_TX_HALT]		   = "EVENT_TX_HALT",
+	[EVENT_RX_HALT]		   = "EVENT_RX_HALT",
+	[EVENT_RX_MEMORY]	   = "EVENT_RX_MEMORY",
+	[EVENT_STS_SPLIT]	   = "EVENT_STS_SPLIT",
+	[EVENT_LINK_RESET]	   = "EVENT_LINK_RESET",
+	[EVENT_RX_PAUSED]	   = "EVENT_RX_PAUSED",
+	[EVENT_DEV_ASLEEP]	   = "EVENT_DEV_ASLEEP",
+	[EVENT_DEV_OPEN]	   = "EVENT_DEV_OPEN",
+	[EVENT_DEVICE_REPORT_IDLE] = "EVENT_DEVICE_REPORT_IDLE",
+	[EVENT_NO_RUNTIME_PM]	   = "EVENT_NO_RUNTIME_PM",
+	[EVENT_RX_KILL]		   = "EVENT_RX_KILL",
+	[EVENT_LINK_CHANGE]	   = "EVENT_LINK_CHANGE",
+	[EVENT_SET_RX_MODE]	   = "EVENT_SET_RX_MODE",
+	[EVENT_NO_IP_ALIGN]	   = "EVENT_NO_IP_ALIGN",
+};
+
+/* handles CDC Ethernet and many other network "bulk data" interfaces */
+int usbnet_get_endpoints(struct usbnet *dev, struct usb_interface *intf)
+{
+	int				tmp;
+	struct usb_host_interface	*alt = NULL;
+	struct usb_host_endpoint	*in = NULL, *out = NULL;
+	struct usb_host_endpoint	*status = NULL;
+
+	for (tmp = 0; tmp < intf->num_altsetting; tmp++) {
+		unsigned	ep;
+
+		in = out = status = NULL;
+		alt = intf->altsetting + tmp;
+
+		/* take the first altsetting with in-bulk + out-bulk;
+		 * remember any status endpoint, just in case;
+		 * ignore other endpoints and altsettings.
+		 */
+		for (ep = 0; ep < alt->desc.bNumEndpoints; ep++) {
+			struct usb_host_endpoint	*e;
+			int				intr = 0;
+
+			e = alt->endpoint + ep;
+
+			/* ignore endpoints which cannot transfer data */
+			if (!usb_endpoint_maxp(&e->desc))
+				continue;
+
+			switch (e->desc.bmAttributes) {
+			case USB_ENDPOINT_XFER_INT:
+				if (!usb_endpoint_dir_in(&e->desc))
+					continue;
+				intr = 1;
+				fallthrough;
+			case USB_ENDPOINT_XFER_BULK:
+				break;
+			default:
+				continue;
+			}
+			if (usb_endpoint_dir_in(&e->desc)) {
+				if (!intr && !in)
+					in = e;
+				else if (intr && !status)
+					status = e;
+			} else {
+				if (!out)
+					out = e;
+			}
+		}
+		if (in && out)
+			break;
+	}
+	if (!alt || !in || !out)
+		return -EINVAL;
+
+	if (alt->desc.bAlternateSetting != 0 ||
+	    !(dev->driver_info->flags & FLAG_NO_SETINT)) {
+		tmp = usb_set_interface (dev->udev, alt->desc.bInterfaceNumber,
+				alt->desc.bAlternateSetting);
+		if (tmp < 0)
+			return tmp;
+	}
+
+	dev->in = usb_rcvbulkpipe (dev->udev,
+			in->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
+	dev->out = usb_sndbulkpipe (dev->udev,
+			out->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
+	dev->status = status;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usbnet_get_endpoints);
+
+int usbnet_get_ethernet_addr(struct usbnet *dev, int iMACAddress)
+{
+	u8		addr[ETH_ALEN];
+	int 		tmp = -1, ret;
+	unsigned char	buf [13];
+
+	ret = usb_string(dev->udev, iMACAddress, buf, sizeof buf);
+	if (ret == 12)
+		tmp = hex2bin(addr, buf, 6);
+	if (tmp < 0) {
+		dev_dbg(&dev->udev->dev,
+			"bad MAC string %d fetch, %d\n", iMACAddress, tmp);
+		if (ret >= 0)
+			ret = -EINVAL;
+		return ret;
+	}
+	eth_hw_addr_set(dev->net, addr);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usbnet_get_ethernet_addr);
+
+static void intr_complete (struct urb *urb)
+{
+	struct usbnet	*dev = urb->context;
+	int		status = urb->status;
+
+	switch (status) {
+	/* success */
+	case 0:
+		dev->driver_info->status(dev, urb);
+		break;
+
+	/* software-driven interface shutdown */
+	case -ENOENT:		/* urb killed */
+	case -ESHUTDOWN:	/* hardware gone */
+		netif_dbg(dev, ifdown, dev->net,
+			  "intr shutdown, code %d\n", status);
+		return;
+
+	/* NOTE:  not throttling like RX/TX, since this endpoint
+	 * already polls infrequently
+	 */
+	default:
+		netdev_dbg(dev->net, "intr status %d\n", status);
+		break;
+	}
+
+	status = usb_submit_urb (urb, GFP_ATOMIC);
+	if (status != 0)
+		netif_err(dev, timer, dev->net,
+			  "intr resubmit --> %d\n", status);
+}
+
+static int init_status (struct usbnet *dev, struct usb_interface *intf)
+{
+	char		*buf = NULL;
+	unsigned	pipe = 0;
+	unsigned	maxp;
+	unsigned	period;
+
+	if (!dev->driver_info->status)
+		return 0;
+
+	pipe = usb_rcvintpipe (dev->udev,
+			dev->status->desc.bEndpointAddress
+				& USB_ENDPOINT_NUMBER_MASK);
+	maxp = usb_maxpacket(dev->udev, pipe);
+
+	/* avoid 1 msec chatter:  min 8 msec poll rate */
+	period = max ((int) dev->status->desc.bInterval,
+		(dev->udev->speed == USB_SPEED_HIGH) ? 7 : 3);
+
+	buf = kmalloc (maxp, GFP_KERNEL);
+	if (buf) {
+		dev->interrupt = usb_alloc_urb (0, GFP_KERNEL);
+		if (!dev->interrupt) {
+			kfree (buf);
+			return -ENOMEM;
+		} else {
+			usb_fill_int_urb(dev->interrupt, dev->udev, pipe,
+				buf, maxp, intr_complete, dev, period);
+			dev->interrupt->transfer_flags |= URB_FREE_BUFFER;
+			dev_dbg(&intf->dev,
+				"status ep%din, %d bytes period %d\n",
+				usb_pipeendpoint(pipe), maxp, period);
+		}
+	}
+	return 0;
+}
+
+/* Submit the interrupt URB if not previously submitted, increasing refcount */
+int usbnet_status_start(struct usbnet *dev, gfp_t mem_flags)
+{
+	int ret = 0;
+
+	WARN_ON_ONCE(dev->interrupt == NULL);
+	if (dev->interrupt) {
+		mutex_lock(&dev->interrupt_mutex);
+
+		if (++dev->interrupt_count == 1)
+			ret = usb_submit_urb(dev->interrupt, mem_flags);
+
+		dev_dbg(&dev->udev->dev, "incremented interrupt URB count to %d\n",
+			dev->interrupt_count);
+		mutex_unlock(&dev->interrupt_mutex);
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usbnet_status_start);
+
+/* For resume; submit interrupt URB if previously submitted */
+static int __usbnet_status_start_force(struct usbnet *dev, gfp_t mem_flags)
+{
+	int ret = 0;
+
+	mutex_lock(&dev->interrupt_mutex);
+	if (dev->interrupt_count) {
+		ret = usb_submit_urb(dev->interrupt, mem_flags);
+		dev_dbg(&dev->udev->dev,
+			"submitted interrupt URB for resume\n");
+	}
+	mutex_unlock(&dev->interrupt_mutex);
+	return ret;
+}
+
+/* Kill the interrupt URB if all submitters want it killed */
+void usbnet_status_stop(struct usbnet *dev)
+{
+	if (dev->interrupt) {
+		mutex_lock(&dev->interrupt_mutex);
+		WARN_ON(dev->interrupt_count == 0);
+
+		if (dev->interrupt_count && --dev->interrupt_count == 0)
+			usb_kill_urb(dev->interrupt);
+
+		dev_dbg(&dev->udev->dev,
+			"decremented interrupt URB count to %d\n",
+			dev->interrupt_count);
+		mutex_unlock(&dev->interrupt_mutex);
+	}
+}
+EXPORT_SYMBOL_GPL(usbnet_status_stop);
+
+/* For suspend; always kill interrupt URB */
+static void __usbnet_status_stop_force(struct usbnet *dev)
+{
+	if (dev->interrupt) {
+		mutex_lock(&dev->interrupt_mutex);
+		usb_kill_urb(dev->interrupt);
+		dev_dbg(&dev->udev->dev, "killed interrupt URB for suspend\n");
+		mutex_unlock(&dev->interrupt_mutex);
+	}
+}
+
+/* Passes this packet up the stack, updating its accounting.
+ * Some link protocols batch packets, so their rx_fixup paths
+ * can return clones as well as just modify the original skb.
+ */
+void usbnet_skb_return (struct usbnet *dev, struct sk_buff *skb)
+{
+	struct pcpu_sw_netstats *stats64 = this_cpu_ptr(dev->net->tstats);
+	unsigned long flags;
+	int	status;
+
+	if (test_bit(EVENT_RX_PAUSED, &dev->flags)) {
+		skb_queue_tail(&dev->rxq_pause, skb);
+		return;
+	}
+
+	/* only update if unset to allow minidriver rx_fixup override */
+	if (skb->protocol == 0)
+		skb->protocol = eth_type_trans (skb, dev->net);
+
+	flags = u64_stats_update_begin_irqsave(&stats64->syncp);
+	u64_stats_inc(&stats64->rx_packets);
+	u64_stats_add(&stats64->rx_bytes, skb->len);
+	u64_stats_update_end_irqrestore(&stats64->syncp, flags);
+
+	netif_dbg(dev, rx_status, dev->net, "< rx, len %zu, type 0x%x\n",
+		  skb->len + sizeof (struct ethhdr), skb->protocol);
+	memset (skb->cb, 0, sizeof (struct skb_data));
+
+	if (skb_defer_rx_timestamp(skb))
+		return;
+
+	status = netif_rx (skb);
+	if (status != NET_RX_SUCCESS)
+		netif_dbg(dev, rx_err, dev->net,
+			  "netif_rx status %d\n", status);
+}
+EXPORT_SYMBOL_GPL(usbnet_skb_return);
+
+/* must be called if hard_mtu or rx_urb_size changed */
+void usbnet_update_max_qlen(struct usbnet *dev)
+{
+	enum usb_device_speed speed = dev->udev->speed;
+
+	if (!dev->rx_urb_size || !dev->hard_mtu)
+		goto insanity;
+	switch (speed) {
+	case USB_SPEED_HIGH:
+		dev->rx_qlen = MAX_QUEUE_MEMORY / dev->rx_urb_size;
+		dev->tx_qlen = MAX_QUEUE_MEMORY / dev->hard_mtu;
+		break;
+	case USB_SPEED_SUPER:
+	case USB_SPEED_SUPER_PLUS:
+		/*
+		 * Not take default 5ms qlen for super speed HC to
+		 * save memory, and iperf tests show 2.5ms qlen can
+		 * work well
+		 */
+		dev->rx_qlen = 5 * MAX_QUEUE_MEMORY / dev->rx_urb_size;
+		dev->tx_qlen = 5 * MAX_QUEUE_MEMORY / dev->hard_mtu;
+		break;
+	default:
+insanity:
+		dev->rx_qlen = dev->tx_qlen = 4;
+	}
+}
+EXPORT_SYMBOL_GPL(usbnet_update_max_qlen);
+
+
+/*-------------------------------------------------------------------------
+ *
+ * Network Device Driver (peer link to "Host Device", from USB host)
+ *
+ *-------------------------------------------------------------------------*/
+
+int usbnet_change_mtu (struct net_device *net, int new_mtu)
+{
+	struct usbnet	*dev = netdev_priv(net);
+	int		ll_mtu = new_mtu + net->hard_header_len;
+	int		old_hard_mtu = dev->hard_mtu;
+	int		old_rx_urb_size = dev->rx_urb_size;
+
+	// no second zero-length packet read wanted after mtu-sized packets
+	if ((ll_mtu % dev->maxpacket) == 0)
+		return -EDOM;
+	net->mtu = new_mtu;
+
+	dev->hard_mtu = net->mtu + net->hard_header_len;
+	if (dev->rx_urb_size == old_hard_mtu) {
+		dev->rx_urb_size = dev->hard_mtu;
+		if (dev->rx_urb_size > old_rx_urb_size) {
+			usbnet_pause_rx(dev);
+			usbnet_unlink_rx_urbs(dev);
+			usbnet_resume_rx(dev);
+		}
+	}
+
+	/* max qlen depend on hard_mtu and rx_urb_size */
+	usbnet_update_max_qlen(dev);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usbnet_change_mtu);
+
+/* The caller must hold list->lock */
+static void __usbnet_queue_skb(struct sk_buff_head *list,
+			struct sk_buff *newsk, enum skb_state state)
+{
+	struct skb_data *entry = (struct skb_data *) newsk->cb;
+
+	__skb_queue_tail(list, newsk);
+	entry->state = state;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* some LK 2.4 HCDs oopsed if we freed or resubmitted urbs from
+ * completion callbacks.  2.5 should have fixed those bugs...
+ */
+
+static enum skb_state defer_bh(struct usbnet *dev, struct sk_buff *skb,
+		struct sk_buff_head *list, enum skb_state state)
+{
+	unsigned long		flags;
+	enum skb_state 		old_state;
+	struct skb_data *entry = (struct skb_data *) skb->cb;
+
+	spin_lock_irqsave(&list->lock, flags);
+	old_state = entry->state;
+	entry->state = state;
+	__skb_unlink(skb, list);
+
+	/* defer_bh() is never called with list == &dev->done.
+	 * spin_lock_nested() tells lockdep that it is OK to take
+	 * dev->done.lock here with list->lock held.
+	 */
+	spin_lock_nested(&dev->done.lock, SINGLE_DEPTH_NESTING);
+
+	__skb_queue_tail(&dev->done, skb);
+	if (dev->done.qlen == 1)
+		tasklet_schedule(&dev->bh);
+	spin_unlock(&dev->done.lock);
+	spin_unlock_irqrestore(&list->lock, flags);
+	return old_state;
+}
+
+/* some work can't be done in tasklets, so we use keventd
+ *
+ * NOTE:  annoying asymmetry:  if it's active, schedule_work() fails,
+ * but tasklet_schedule() doesn't.  hope the failure is rare.
+ */
+void usbnet_defer_kevent (struct usbnet *dev, int work)
+{
+	set_bit (work, &dev->flags);
+	if (!schedule_work (&dev->kevent))
+		netdev_dbg(dev->net, "kevent %s may have been dropped\n", usbnet_event_names[work]);
+	else
+		netdev_dbg(dev->net, "kevent %s scheduled\n", usbnet_event_names[work]);
+}
+EXPORT_SYMBOL_GPL(usbnet_defer_kevent);
+
+/*-------------------------------------------------------------------------*/
+
+static void rx_complete (struct urb *urb);
+
+static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
+{
+	struct sk_buff		*skb;
+	struct skb_data		*entry;
+	int			retval = 0;
+	unsigned long		lockflags;
+	size_t			size = dev->rx_urb_size;
+
+	/* prevent rx skb allocation when error ratio is high */
+	if (test_bit(EVENT_RX_KILL, &dev->flags)) {
+		usb_free_urb(urb);
+		return -ENOLINK;
+	}
+
+	if (test_bit(EVENT_NO_IP_ALIGN, &dev->flags))
+		skb = __netdev_alloc_skb(dev->net, size, flags);
+	else
+		skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
+	if (!skb) {
+		netif_dbg(dev, rx_err, dev->net, "no rx skb\n");
+		usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
+		usb_free_urb (urb);
+		return -ENOMEM;
+	}
+
+	entry = (struct skb_data *) skb->cb;
+	entry->urb = urb;
+	entry->dev = dev;
+	entry->length = 0;
+
+	usb_fill_bulk_urb (urb, dev->udev, dev->in,
+		skb->data, size, rx_complete, skb);
+
+	spin_lock_irqsave (&dev->rxq.lock, lockflags);
+
+	if (netif_running (dev->net) &&
+	    netif_device_present (dev->net) &&
+	    test_bit(EVENT_DEV_OPEN, &dev->flags) &&
+	    !test_bit (EVENT_RX_HALT, &dev->flags) &&
+	    !test_bit (EVENT_DEV_ASLEEP, &dev->flags)) {
+		switch (retval = usb_submit_urb (urb, GFP_ATOMIC)) {
+		case -EPIPE:
+			usbnet_defer_kevent (dev, EVENT_RX_HALT);
+			break;
+		case -ENOMEM:
+			usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
+			break;
+		case -ENODEV:
+			netif_dbg(dev, ifdown, dev->net, "device gone\n");
+			netif_device_detach (dev->net);
+			break;
+		case -EHOSTUNREACH:
+			retval = -ENOLINK;
+			break;
+		default:
+			netif_dbg(dev, rx_err, dev->net,
+				  "rx submit, %d\n", retval);
+			tasklet_schedule (&dev->bh);
+			break;
+		case 0:
+			__usbnet_queue_skb(&dev->rxq, skb, rx_start);
+		}
+	} else {
+		netif_dbg(dev, ifdown, dev->net, "rx: stopped\n");
+		retval = -ENOLINK;
+	}
+	spin_unlock_irqrestore (&dev->rxq.lock, lockflags);
+	if (retval) {
+		dev_kfree_skb_any (skb);
+		usb_free_urb (urb);
+	}
+	return retval;
+}
+
+
+/*-------------------------------------------------------------------------*/
+
+static inline int rx_process(struct usbnet *dev, struct sk_buff *skb)
+{
+	if (dev->driver_info->rx_fixup &&
+	    !dev->driver_info->rx_fixup (dev, skb)) {
+		/* With RX_ASSEMBLE, rx_fixup() must update counters */
+		if (!(dev->driver_info->flags & FLAG_RX_ASSEMBLE))
+			dev->net->stats.rx_errors++;
+		return -EPROTO;
+	}
+	// else network stack removes extra byte if we forced a short packet
+
+	/* all data was already cloned from skb inside the driver */
+	if (dev->driver_info->flags & FLAG_MULTI_PACKET)
+		return -EALREADY;
+
+	if (skb->len < ETH_HLEN) {
+		dev->net->stats.rx_errors++;
+		dev->net->stats.rx_length_errors++;
+		netif_dbg(dev, rx_err, dev->net, "rx length %d\n", skb->len);
+		return -EPROTO;
+	}
+
+	usbnet_skb_return(dev, skb);
+	return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void rx_complete (struct urb *urb)
+{
+	struct sk_buff		*skb = (struct sk_buff *) urb->context;
+	struct skb_data		*entry = (struct skb_data *) skb->cb;
+	struct usbnet		*dev = entry->dev;
+	int			urb_status = urb->status;
+	enum skb_state		state;
+
+	skb_put (skb, urb->actual_length);
+	state = rx_done;
+	entry->urb = NULL;
+
+	switch (urb_status) {
+	/* success */
+	case 0:
+		break;
+
+	/* stalls need manual reset. this is rare ... except that
+	 * when going through USB 2.0 TTs, unplug appears this way.
+	 * we avoid the highspeed version of the ETIMEDOUT/EILSEQ
+	 * storm, recovering as needed.
+	 */
+	case -EPIPE:
+		dev->net->stats.rx_errors++;
+		usbnet_defer_kevent (dev, EVENT_RX_HALT);
+		fallthrough;
+
+	/* software-driven interface shutdown */
+	case -ECONNRESET:		/* async unlink */
+	case -ESHUTDOWN:		/* hardware gone */
+		netif_dbg(dev, ifdown, dev->net,
+			  "rx shutdown, code %d\n", urb_status);
+		goto block;
+
+	/* we get controller i/o faults during hub_wq disconnect() delays.
+	 * throttle down resubmits, to avoid log floods; just temporarily,
+	 * so we still recover when the fault isn't a hub_wq delay.
+	 */
+	case -EPROTO:
+	case -ETIME:
+	case -EILSEQ:
+		dev->net->stats.rx_errors++;
+		if (!timer_pending (&dev->delay)) {
+			mod_timer (&dev->delay, jiffies + THROTTLE_JIFFIES);
+			netif_dbg(dev, link, dev->net,
+				  "rx throttle %d\n", urb_status);
+		}
+block:
+		state = rx_cleanup;
+		entry->urb = urb;
+		urb = NULL;
+		break;
+
+	/* data overrun ... flush fifo? */
+	case -EOVERFLOW:
+		dev->net->stats.rx_over_errors++;
+		fallthrough;
+
+	default:
+		state = rx_cleanup;
+		dev->net->stats.rx_errors++;
+		netif_dbg(dev, rx_err, dev->net, "rx status %d\n", urb_status);
+		break;
+	}
+
+	/* stop rx if packet error rate is high */
+	if (++dev->pkt_cnt > 30) {
+		dev->pkt_cnt = 0;
+		dev->pkt_err = 0;
+	} else {
+		if (state == rx_cleanup)
+			dev->pkt_err++;
+		if (dev->pkt_err > 20)
+			set_bit(EVENT_RX_KILL, &dev->flags);
+	}
+
+	state = defer_bh(dev, skb, &dev->rxq, state);
+
+	if (urb) {
+		if (netif_running (dev->net) &&
+		    !test_bit (EVENT_RX_HALT, &dev->flags) &&
+		    state != unlink_start) {
+			rx_submit (dev, urb, GFP_ATOMIC);
+			usb_mark_last_busy(dev->udev);
+			return;
+		}
+		usb_free_urb (urb);
+	}
+	netif_dbg(dev, rx_err, dev->net, "no read resubmitted\n");
+}
+
+/*-------------------------------------------------------------------------*/
+void usbnet_pause_rx(struct usbnet *dev)
+{
+	set_bit(EVENT_RX_PAUSED, &dev->flags);
+
+	netif_dbg(dev, rx_status, dev->net, "paused rx queue enabled\n");
+}
+EXPORT_SYMBOL_GPL(usbnet_pause_rx);
+
+void usbnet_resume_rx(struct usbnet *dev)
+{
+	struct sk_buff *skb;
+	int num = 0;
+
+	clear_bit(EVENT_RX_PAUSED, &dev->flags);
+
+	while ((skb = skb_dequeue(&dev->rxq_pause)) != NULL) {
+		usbnet_skb_return(dev, skb);
+		num++;
+	}
+
+	tasklet_schedule(&dev->bh);
+
+	netif_dbg(dev, rx_status, dev->net,
+		  "paused rx queue disabled, %d skbs requeued\n", num);
+}
+EXPORT_SYMBOL_GPL(usbnet_resume_rx);
+
+void usbnet_purge_paused_rxq(struct usbnet *dev)
+{
+	skb_queue_purge(&dev->rxq_pause);
+}
+EXPORT_SYMBOL_GPL(usbnet_purge_paused_rxq);
+
+/*-------------------------------------------------------------------------*/
+
+// unlink pending rx/tx; completion handlers do all other cleanup
+
+static int unlink_urbs (struct usbnet *dev, struct sk_buff_head *q)
+{
+	unsigned long		flags;
+	struct sk_buff		*skb;
+	int			count = 0;
+
+	spin_lock_irqsave (&q->lock, flags);
+	while (!skb_queue_empty(q)) {
+		struct skb_data		*entry;
+		struct urb		*urb;
+		int			retval;
+
+		skb_queue_walk(q, skb) {
+			entry = (struct skb_data *) skb->cb;
+			if (entry->state != unlink_start)
+				goto found;
+		}
+		break;
+found:
+		entry->state = unlink_start;
+		urb = entry->urb;
+
+		/*
+		 * Get reference count of the URB to avoid it to be
+		 * freed during usb_unlink_urb, which may trigger
+		 * use-after-free problem inside usb_unlink_urb since
+		 * usb_unlink_urb is always racing with .complete
+		 * handler(include defer_bh).
+		 */
+		usb_get_urb(urb);
+		spin_unlock_irqrestore(&q->lock, flags);
+		// during some PM-driven resume scenarios,
+		// these (async) unlinks complete immediately
+		retval = usb_unlink_urb (urb);
+		if (retval != -EINPROGRESS && retval != 0)
+			netdev_dbg(dev->net, "unlink urb err, %d\n", retval);
+		else
+			count++;
+		usb_put_urb(urb);
+		spin_lock_irqsave(&q->lock, flags);
+	}
+	spin_unlock_irqrestore (&q->lock, flags);
+	return count;
+}
+
+// Flush all pending rx urbs
+// minidrivers may need to do this when the MTU changes
+
+void usbnet_unlink_rx_urbs(struct usbnet *dev)
+{
+	if (netif_running(dev->net)) {
+		(void) unlink_urbs (dev, &dev->rxq);
+		tasklet_schedule(&dev->bh);
+	}
+}
+EXPORT_SYMBOL_GPL(usbnet_unlink_rx_urbs);
+
+/*-------------------------------------------------------------------------*/
+
+static void wait_skb_queue_empty(struct sk_buff_head *q)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&q->lock, flags);
+	while (!skb_queue_empty(q)) {
+		spin_unlock_irqrestore(&q->lock, flags);
+		schedule_timeout(msecs_to_jiffies(UNLINK_TIMEOUT_MS));
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		spin_lock_irqsave(&q->lock, flags);
+	}
+	spin_unlock_irqrestore(&q->lock, flags);
+}
+
+// precondition: never called in_interrupt
+static void usbnet_terminate_urbs(struct usbnet *dev)
+{
+	DECLARE_WAITQUEUE(wait, current);
+	int temp;
+
+	/* ensure there are no more active urbs */
+	add_wait_queue(&dev->wait, &wait);
+	set_current_state(TASK_UNINTERRUPTIBLE);
+	temp = unlink_urbs(dev, &dev->txq) +
+		unlink_urbs(dev, &dev->rxq);
+
+	/* maybe wait for deletions to finish. */
+	wait_skb_queue_empty(&dev->rxq);
+	wait_skb_queue_empty(&dev->txq);
+	wait_skb_queue_empty(&dev->done);
+	netif_dbg(dev, ifdown, dev->net,
+		  "waited for %d urb completions\n", temp);
+	set_current_state(TASK_RUNNING);
+	remove_wait_queue(&dev->wait, &wait);
+}
+
+int usbnet_stop (struct net_device *net)
+{
+	struct usbnet		*dev = netdev_priv(net);
+	const struct driver_info *info = dev->driver_info;
+	int			retval, pm, mpn;
+
+	clear_bit(EVENT_DEV_OPEN, &dev->flags);
+	netif_stop_queue (net);
+
+	netif_info(dev, ifdown, dev->net,
+		   "stop stats: rx/tx %lu/%lu, errs %lu/%lu\n",
+		   net->stats.rx_packets, net->stats.tx_packets,
+		   net->stats.rx_errors, net->stats.tx_errors);
+
+	/* to not race resume */
+	pm = usb_autopm_get_interface(dev->intf);
+	/* allow minidriver to stop correctly (wireless devices to turn off
+	 * radio etc) */
+	if (info->stop) {
+		retval = info->stop(dev);
+		if (retval < 0)
+			netif_info(dev, ifdown, dev->net,
+				   "stop fail (%d) usbnet usb-%s-%s, %s\n",
+				   retval,
+				   dev->udev->bus->bus_name, dev->udev->devpath,
+				   info->description);
+	}
+
+	if (!(info->flags & FLAG_AVOID_UNLINK_URBS))
+		usbnet_terminate_urbs(dev);
+
+	usbnet_status_stop(dev);
+
+	usbnet_purge_paused_rxq(dev);
+
+	mpn = !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags);
+
+	/* deferred work (timer, softirq, task) must also stop */
+	dev->flags = 0;
+	del_timer_sync (&dev->delay);
+	tasklet_kill (&dev->bh);
+	cancel_work_sync(&dev->kevent);
+	if (!pm)
+		usb_autopm_put_interface(dev->intf);
+
+	if (info->manage_power && mpn)
+		info->manage_power(dev, 0);
+	else
+		usb_autopm_put_interface(dev->intf);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usbnet_stop);
+
+/*-------------------------------------------------------------------------*/
+
+// posts reads, and enables write queuing
+
+// precondition: never called in_interrupt
+
+int usbnet_open (struct net_device *net)
+{
+	struct usbnet		*dev = netdev_priv(net);
+	int			retval;
+	const struct driver_info *info = dev->driver_info;
+
+	if ((retval = usb_autopm_get_interface(dev->intf)) < 0) {
+		netif_info(dev, ifup, dev->net,
+			   "resumption fail (%d) usbnet usb-%s-%s, %s\n",
+			   retval,
+			   dev->udev->bus->bus_name,
+			   dev->udev->devpath,
+			   info->description);
+		goto done_nopm;
+	}
+
+	// put into "known safe" state
+	if (info->reset && (retval = info->reset (dev)) < 0) {
+		netif_info(dev, ifup, dev->net,
+			   "open reset fail (%d) usbnet usb-%s-%s, %s\n",
+			   retval,
+			   dev->udev->bus->bus_name,
+			   dev->udev->devpath,
+			   info->description);
+		goto done;
+	}
+
+	/* hard_mtu or rx_urb_size may change in reset() */
+	usbnet_update_max_qlen(dev);
+
+	// insist peer be connected
+	if (info->check_connect && (retval = info->check_connect (dev)) < 0) {
+		netif_err(dev, ifup, dev->net, "can't open; %d\n", retval);
+		goto done;
+	}
+
+	/* start any status interrupt transfer */
+	if (dev->interrupt) {
+		retval = usbnet_status_start(dev, GFP_KERNEL);
+		if (retval < 0) {
+			netif_err(dev, ifup, dev->net,
+				  "intr submit %d\n", retval);
+			goto done;
+		}
+	}
+
+	set_bit(EVENT_DEV_OPEN, &dev->flags);
+	netif_start_queue (net);
+	netif_info(dev, ifup, dev->net,
+		   "open: enable queueing (rx %d, tx %d) mtu %d %s framing\n",
+		   (int)RX_QLEN(dev), (int)TX_QLEN(dev),
+		   dev->net->mtu,
+		   (dev->driver_info->flags & FLAG_FRAMING_NC) ? "NetChip" :
+		   (dev->driver_info->flags & FLAG_FRAMING_GL) ? "GeneSys" :
+		   (dev->driver_info->flags & FLAG_FRAMING_Z) ? "Zaurus" :
+		   (dev->driver_info->flags & FLAG_FRAMING_RN) ? "RNDIS" :
+		   (dev->driver_info->flags & FLAG_FRAMING_AX) ? "ASIX" :
+		   "simple");
+
+	/* reset rx error state */
+	dev->pkt_cnt = 0;
+	dev->pkt_err = 0;
+	clear_bit(EVENT_RX_KILL, &dev->flags);
+
+	// delay posting reads until we're fully open
+	tasklet_schedule (&dev->bh);
+	if (info->manage_power) {
+		retval = info->manage_power(dev, 1);
+		if (retval < 0) {
+			retval = 0;
+			set_bit(EVENT_NO_RUNTIME_PM, &dev->flags);
+		} else {
+			usb_autopm_put_interface(dev->intf);
+		}
+	}
+	return retval;
+done:
+	usb_autopm_put_interface(dev->intf);
+done_nopm:
+	return retval;
+}
+EXPORT_SYMBOL_GPL(usbnet_open);
+
+/*-------------------------------------------------------------------------*/
+
+/* ethtool methods; minidrivers may need to add some more, but
+ * they'll probably want to use this base set.
+ */
+
+/* These methods are written on the assumption that the device
+ * uses MII
+ */
+int usbnet_get_link_ksettings_mii(struct net_device *net,
+			      struct ethtool_link_ksettings *cmd)
+{
+	struct usbnet *dev = netdev_priv(net);
+
+	if (!dev->mii.mdio_read)
+		return -EOPNOTSUPP;
+
+	mii_ethtool_get_link_ksettings(&dev->mii, cmd);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usbnet_get_link_ksettings_mii);
+
+int usbnet_get_link_ksettings_internal(struct net_device *net,
+					struct ethtool_link_ksettings *cmd)
+{
+	struct usbnet *dev = netdev_priv(net);
+
+	/* the assumption that speed is equal on tx and rx
+	 * is deeply engrained into the networking layer.
+	 * For wireless stuff it is not true.
+	 * We assume that rx_speed matters more.
+	 */
+	if (dev->rx_speed != SPEED_UNSET)
+		cmd->base.speed = dev->rx_speed / 1000000;
+	else if (dev->tx_speed != SPEED_UNSET)
+		cmd->base.speed = dev->tx_speed / 1000000;
+	else
+		cmd->base.speed = SPEED_UNKNOWN;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usbnet_get_link_ksettings_internal);
+
+int usbnet_set_link_ksettings_mii(struct net_device *net,
+			      const struct ethtool_link_ksettings *cmd)
+{
+	struct usbnet *dev = netdev_priv(net);
+	int retval;
+
+	if (!dev->mii.mdio_write)
+		return -EOPNOTSUPP;
+
+	retval = mii_ethtool_set_link_ksettings(&dev->mii, cmd);
+
+	/* link speed/duplex might have changed */
+	if (dev->driver_info->link_reset)
+		dev->driver_info->link_reset(dev);
+
+	/* hard_mtu or rx_urb_size may change in link_reset() */
+	usbnet_update_max_qlen(dev);
+
+	return retval;
+}
+EXPORT_SYMBOL_GPL(usbnet_set_link_ksettings_mii);
+
+u32 usbnet_get_link (struct net_device *net)
+{
+	struct usbnet *dev = netdev_priv(net);
+
+	/* If a check_connect is defined, return its result */
+	if (dev->driver_info->check_connect)
+		return dev->driver_info->check_connect (dev) == 0;
+
+	/* if the device has mii operations, use those */
+	if (dev->mii.mdio_read)
+		return mii_link_ok(&dev->mii);
+
+	/* Otherwise, dtrt for drivers calling netif_carrier_{on,off} */
+	return ethtool_op_get_link(net);
+}
+EXPORT_SYMBOL_GPL(usbnet_get_link);
+
+int usbnet_nway_reset(struct net_device *net)
+{
+	struct usbnet *dev = netdev_priv(net);
+
+	if (!dev->mii.mdio_write)
+		return -EOPNOTSUPP;
+
+	return mii_nway_restart(&dev->mii);
+}
+EXPORT_SYMBOL_GPL(usbnet_nway_reset);
+
+void usbnet_get_drvinfo (struct net_device *net, struct ethtool_drvinfo *info)
+{
+	struct usbnet *dev = netdev_priv(net);
+
+	strscpy(info->driver, dev->driver_name, sizeof(info->driver));
+	strscpy(info->fw_version, dev->driver_info->description,
+		sizeof(info->fw_version));
+	usb_make_path (dev->udev, info->bus_info, sizeof info->bus_info);
+}
+EXPORT_SYMBOL_GPL(usbnet_get_drvinfo);
+
+u32 usbnet_get_msglevel (struct net_device *net)
+{
+	struct usbnet *dev = netdev_priv(net);
+
+	return dev->msg_enable;
+}
+EXPORT_SYMBOL_GPL(usbnet_get_msglevel);
+
+void usbnet_set_msglevel (struct net_device *net, u32 level)
+{
+	struct usbnet *dev = netdev_priv(net);
+
+	dev->msg_enable = level;
+}
+EXPORT_SYMBOL_GPL(usbnet_set_msglevel);
+
+/* drivers may override default ethtool_ops in their bind() routine */
+static const struct ethtool_ops usbnet_ethtool_ops = {
+	.get_link		= usbnet_get_link,
+	.nway_reset		= usbnet_nway_reset,
+	.get_drvinfo		= usbnet_get_drvinfo,
+	.get_msglevel		= usbnet_get_msglevel,
+	.set_msglevel		= usbnet_set_msglevel,
+	.get_ts_info		= ethtool_op_get_ts_info,
+	.get_link_ksettings	= usbnet_get_link_ksettings_mii,
+	.set_link_ksettings	= usbnet_set_link_ksettings_mii,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static void __handle_link_change(struct usbnet *dev)
+{
+	if (!test_bit(EVENT_DEV_OPEN, &dev->flags))
+		return;
+
+	if (!netif_carrier_ok(dev->net)) {
+		/* kill URBs for reading packets to save bus bandwidth */
+		unlink_urbs(dev, &dev->rxq);
+
+		/*
+		 * tx_timeout will unlink URBs for sending packets and
+		 * tx queue is stopped by netcore after link becomes off
+		 */
+	} else {
+		/* submitting URBs for reading packets */
+		tasklet_schedule(&dev->bh);
+	}
+
+	/* hard_mtu or rx_urb_size may change during link change */
+	usbnet_update_max_qlen(dev);
+
+	clear_bit(EVENT_LINK_CHANGE, &dev->flags);
+}
+
+void usbnet_set_rx_mode(struct net_device *net)
+{
+	struct usbnet		*dev = netdev_priv(net);
+
+	usbnet_defer_kevent(dev, EVENT_SET_RX_MODE);
+}
+EXPORT_SYMBOL_GPL(usbnet_set_rx_mode);
+
+static void __handle_set_rx_mode(struct usbnet *dev)
+{
+	if (dev->driver_info->set_rx_mode)
+		(dev->driver_info->set_rx_mode)(dev);
+
+	clear_bit(EVENT_SET_RX_MODE, &dev->flags);
+}
+
+/* work that cannot be done in interrupt context uses keventd.
+ *
+ * NOTE:  with 2.5 we could do more of this using completion callbacks,
+ * especially now that control transfers can be queued.
+ */
+static void
+usbnet_deferred_kevent (struct work_struct *work)
+{
+	struct usbnet		*dev =
+		container_of(work, struct usbnet, kevent);
+	int			status;
+
+	/* usb_clear_halt() needs a thread context */
+	if (test_bit (EVENT_TX_HALT, &dev->flags)) {
+		unlink_urbs (dev, &dev->txq);
+		status = usb_autopm_get_interface(dev->intf);
+		if (status < 0)
+			goto fail_pipe;
+		status = usb_clear_halt (dev->udev, dev->out);
+		usb_autopm_put_interface(dev->intf);
+		if (status < 0 &&
+		    status != -EPIPE &&
+		    status != -ESHUTDOWN) {
+			if (netif_msg_tx_err (dev))
+fail_pipe:
+				netdev_err(dev->net, "can't clear tx halt, status %d\n",
+					   status);
+		} else {
+			clear_bit (EVENT_TX_HALT, &dev->flags);
+			if (status != -ESHUTDOWN)
+				netif_wake_queue (dev->net);
+		}
+	}
+	if (test_bit (EVENT_RX_HALT, &dev->flags)) {
+		unlink_urbs (dev, &dev->rxq);
+		status = usb_autopm_get_interface(dev->intf);
+		if (status < 0)
+			goto fail_halt;
+		status = usb_clear_halt (dev->udev, dev->in);
+		usb_autopm_put_interface(dev->intf);
+		if (status < 0 &&
+		    status != -EPIPE &&
+		    status != -ESHUTDOWN) {
+			if (netif_msg_rx_err (dev))
+fail_halt:
+				netdev_err(dev->net, "can't clear rx halt, status %d\n",
+					   status);
+		} else {
+			clear_bit (EVENT_RX_HALT, &dev->flags);
+			tasklet_schedule (&dev->bh);
+		}
+	}
+
+	/* tasklet could resubmit itself forever if memory is tight */
+	if (test_bit (EVENT_RX_MEMORY, &dev->flags)) {
+		struct urb	*urb = NULL;
+		int resched = 1;
+
+		if (netif_running (dev->net))
+			urb = usb_alloc_urb (0, GFP_KERNEL);
+		else
+			clear_bit (EVENT_RX_MEMORY, &dev->flags);
+		if (urb != NULL) {
+			clear_bit (EVENT_RX_MEMORY, &dev->flags);
+			status = usb_autopm_get_interface(dev->intf);
+			if (status < 0) {
+				usb_free_urb(urb);
+				goto fail_lowmem;
+			}
+			if (rx_submit (dev, urb, GFP_KERNEL) == -ENOLINK)
+				resched = 0;
+			usb_autopm_put_interface(dev->intf);
+fail_lowmem:
+			if (resched)
+				tasklet_schedule (&dev->bh);
+		}
+	}
+
+	if (test_bit (EVENT_LINK_RESET, &dev->flags)) {
+		const struct driver_info *info = dev->driver_info;
+		int			retval = 0;
+
+		clear_bit (EVENT_LINK_RESET, &dev->flags);
+		status = usb_autopm_get_interface(dev->intf);
+		if (status < 0)
+			goto skip_reset;
+		if(info->link_reset && (retval = info->link_reset(dev)) < 0) {
+			usb_autopm_put_interface(dev->intf);
+skip_reset:
+			netdev_info(dev->net, "link reset failed (%d) usbnet usb-%s-%s, %s\n",
+				    retval,
+				    dev->udev->bus->bus_name,
+				    dev->udev->devpath,
+				    info->description);
+		} else {
+			usb_autopm_put_interface(dev->intf);
+		}
+
+		/* handle link change from link resetting */
+		__handle_link_change(dev);
+	}
+
+	if (test_bit (EVENT_LINK_CHANGE, &dev->flags))
+		__handle_link_change(dev);
+
+	if (test_bit (EVENT_SET_RX_MODE, &dev->flags))
+		__handle_set_rx_mode(dev);
+
+
+	if (dev->flags)
+		netdev_dbg(dev->net, "kevent done, flags = 0x%lx\n", dev->flags);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void tx_complete (struct urb *urb)
+{
+	struct sk_buff		*skb = (struct sk_buff *) urb->context;
+	struct skb_data		*entry = (struct skb_data *) skb->cb;
+	struct usbnet		*dev = entry->dev;
+
+	if (urb->status == 0) {
+		struct pcpu_sw_netstats *stats64 = this_cpu_ptr(dev->net->tstats);
+		unsigned long flags;
+
+		flags = u64_stats_update_begin_irqsave(&stats64->syncp);
+		u64_stats_add(&stats64->tx_packets, entry->packets);
+		u64_stats_add(&stats64->tx_bytes, entry->length);
+		u64_stats_update_end_irqrestore(&stats64->syncp, flags);
+	} else {
+		dev->net->stats.tx_errors++;
+
+		switch (urb->status) {
+		case -EPIPE:
+			usbnet_defer_kevent (dev, EVENT_TX_HALT);
+			break;
+
+		/* software-driven interface shutdown */
+		case -ECONNRESET:		// async unlink
+		case -ESHUTDOWN:		// hardware gone
+			break;
+
+		/* like rx, tx gets controller i/o faults during hub_wq
+		 * delays and so it uses the same throttling mechanism.
+		 */
+		case -EPROTO:
+		case -ETIME:
+		case -EILSEQ:
+			usb_mark_last_busy(dev->udev);
+			if (!timer_pending (&dev->delay)) {
+				mod_timer (&dev->delay,
+					jiffies + THROTTLE_JIFFIES);
+				netif_dbg(dev, link, dev->net,
+					  "tx throttle %d\n", urb->status);
+			}
+			netif_stop_queue (dev->net);
+			break;
+		default:
+			netif_dbg(dev, tx_err, dev->net,
+				  "tx err %d\n", entry->urb->status);
+			break;
+		}
+	}
+
+	usb_autopm_put_interface_async(dev->intf);
+	(void) defer_bh(dev, skb, &dev->txq, tx_done);
+}
+
+/*-------------------------------------------------------------------------*/
+
+void usbnet_tx_timeout (struct net_device *net, unsigned int txqueue)
+{
+	struct usbnet		*dev = netdev_priv(net);
+
+	unlink_urbs (dev, &dev->txq);
+	tasklet_schedule (&dev->bh);
+	/* this needs to be handled individually because the generic layer
+	 * doesn't know what is sufficient and could not restore private
+	 * information if a remedy of an unconditional reset were used.
+	 */
+	if (dev->driver_info->recover)
+		(dev->driver_info->recover)(dev);
+}
+EXPORT_SYMBOL_GPL(usbnet_tx_timeout);
+
+/*-------------------------------------------------------------------------*/
+
+static int build_dma_sg(const struct sk_buff *skb, struct urb *urb)
+{
+	unsigned num_sgs, total_len = 0;
+	int i, s = 0;
+
+	num_sgs = skb_shinfo(skb)->nr_frags + 1;
+	if (num_sgs == 1)
+		return 0;
+
+	/* reserve one for zero packet */
+	urb->sg = kmalloc_array(num_sgs + 1, sizeof(struct scatterlist),
+				GFP_ATOMIC);
+	if (!urb->sg)
+		return -ENOMEM;
+
+	urb->num_sgs = num_sgs;
+	sg_init_table(urb->sg, urb->num_sgs + 1);
+
+	sg_set_buf(&urb->sg[s++], skb->data, skb_headlen(skb));
+	total_len += skb_headlen(skb);
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		skb_frag_t *f = &skb_shinfo(skb)->frags[i];
+
+		total_len += skb_frag_size(f);
+		sg_set_page(&urb->sg[i + s], skb_frag_page(f), skb_frag_size(f),
+			    skb_frag_off(f));
+	}
+	urb->transfer_buffer_length = total_len;
+
+	return 1;
+}
+
+netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
+				     struct net_device *net)
+{
+	struct usbnet		*dev = netdev_priv(net);
+	unsigned int			length;
+	struct urb		*urb = NULL;
+	struct skb_data		*entry;
+	const struct driver_info *info = dev->driver_info;
+	unsigned long		flags;
+	int retval;
+
+	if (skb)
+		skb_tx_timestamp(skb);
+
+	// some devices want funky USB-level framing, for
+	// win32 driver (usually) and/or hardware quirks
+	if (info->tx_fixup) {
+		skb = info->tx_fixup (dev, skb, GFP_ATOMIC);
+		if (!skb) {
+			/* packet collected; minidriver waiting for more */
+			if (info->flags & FLAG_MULTI_PACKET)
+				goto not_drop;
+			netif_dbg(dev, tx_err, dev->net, "can't tx_fixup skb\n");
+			goto drop;
+		}
+	}
+
+	if (!(urb = usb_alloc_urb (0, GFP_ATOMIC))) {
+		netif_dbg(dev, tx_err, dev->net, "no urb\n");
+		goto drop;
+	}
+
+	entry = (struct skb_data *) skb->cb;
+	entry->urb = urb;
+	entry->dev = dev;
+
+	usb_fill_bulk_urb (urb, dev->udev, dev->out,
+			skb->data, skb->len, tx_complete, skb);
+	if (dev->can_dma_sg) {
+		if (build_dma_sg(skb, urb) < 0)
+			goto drop;
+	}
+	length = urb->transfer_buffer_length;
+
+	/* don't assume the hardware handles USB_ZERO_PACKET
+	 * NOTE:  strictly conforming cdc-ether devices should expect
+	 * the ZLP here, but ignore the one-byte packet.
+	 * NOTE2: CDC NCM specification is different from CDC ECM when
+	 * handling ZLP/short packets, so cdc_ncm driver will make short
+	 * packet itself if needed.
+	 */
+	if (length % dev->maxpacket == 0) {
+		if (!(info->flags & FLAG_SEND_ZLP)) {
+			if (!(info->flags & FLAG_MULTI_PACKET)) {
+				length++;
+				if (skb_tailroom(skb) && !urb->num_sgs) {
+					skb->data[skb->len] = 0;
+					__skb_put(skb, 1);
+				} else if (urb->num_sgs)
+					sg_set_buf(&urb->sg[urb->num_sgs++],
+							dev->padding_pkt, 1);
+			}
+		} else
+			urb->transfer_flags |= URB_ZERO_PACKET;
+	}
+	urb->transfer_buffer_length = length;
+
+	if (info->flags & FLAG_MULTI_PACKET) {
+		/* Driver has set number of packets and a length delta.
+		 * Calculate the complete length and ensure that it's
+		 * positive.
+		 */
+		entry->length += length;
+		if (WARN_ON_ONCE(entry->length <= 0))
+			entry->length = length;
+	} else {
+		usbnet_set_skb_tx_stats(skb, 1, length);
+	}
+
+	spin_lock_irqsave(&dev->txq.lock, flags);
+	retval = usb_autopm_get_interface_async(dev->intf);
+	if (retval < 0) {
+		spin_unlock_irqrestore(&dev->txq.lock, flags);
+		goto drop;
+	}
+	if (netif_queue_stopped(net)) {
+		usb_autopm_put_interface_async(dev->intf);
+		spin_unlock_irqrestore(&dev->txq.lock, flags);
+		goto drop;
+	}
+
+#ifdef CONFIG_PM
+	/* if this triggers the device is still a sleep */
+	if (test_bit(EVENT_DEV_ASLEEP, &dev->flags)) {
+		/* transmission will be done in resume */
+		usb_anchor_urb(urb, &dev->deferred);
+		/* no use to process more packets */
+		netif_stop_queue(net);
+		usb_put_urb(urb);
+		spin_unlock_irqrestore(&dev->txq.lock, flags);
+		netdev_dbg(dev->net, "Delaying transmission for resumption\n");
+		goto deferred;
+	}
+#endif
+
+	switch ((retval = usb_submit_urb (urb, GFP_ATOMIC))) {
+	case -EPIPE:
+		netif_stop_queue (net);
+		usbnet_defer_kevent (dev, EVENT_TX_HALT);
+		usb_autopm_put_interface_async(dev->intf);
+		break;
+	default:
+		usb_autopm_put_interface_async(dev->intf);
+		netif_dbg(dev, tx_err, dev->net,
+			  "tx: submit urb err %d\n", retval);
+		break;
+	case 0:
+		netif_trans_update(net);
+		__usbnet_queue_skb(&dev->txq, skb, tx_start);
+		if (dev->txq.qlen >= TX_QLEN (dev))
+			netif_stop_queue (net);
+	}
+	spin_unlock_irqrestore (&dev->txq.lock, flags);
+
+	if (retval) {
+		netif_dbg(dev, tx_err, dev->net, "drop, code %d\n", retval);
+drop:
+		dev->net->stats.tx_dropped++;
+not_drop:
+		if (skb)
+			dev_kfree_skb_any (skb);
+		if (urb) {
+			kfree(urb->sg);
+			usb_free_urb(urb);
+		}
+	} else
+		netif_dbg(dev, tx_queued, dev->net,
+			  "> tx, len %u, type 0x%x\n", length, skb->protocol);
+#ifdef CONFIG_PM
+deferred:
+#endif
+	return NETDEV_TX_OK;
+}
+EXPORT_SYMBOL_GPL(usbnet_start_xmit);
+
+static int rx_alloc_submit(struct usbnet *dev, gfp_t flags)
+{
+	struct urb	*urb;
+	int		i;
+	int		ret = 0;
+
+	/* don't refill the queue all at once */
+	for (i = 0; i < 10 && dev->rxq.qlen < RX_QLEN(dev); i++) {
+		urb = usb_alloc_urb(0, flags);
+		if (urb != NULL) {
+			ret = rx_submit(dev, urb, flags);
+			if (ret)
+				goto err;
+		} else {
+			ret = -ENOMEM;
+			goto err;
+		}
+	}
+err:
+	return ret;
+}
+
+static inline void usb_free_skb(struct sk_buff *skb)
+{
+	struct skb_data *entry = (struct skb_data *)skb->cb;
+
+	usb_free_urb(entry->urb);
+	dev_kfree_skb(skb);
+}
+
+/*-------------------------------------------------------------------------*/
+
+// tasklet (work deferred from completions, in_irq) or timer
+
+static void usbnet_bh (struct timer_list *t)
+{
+	struct usbnet		*dev = from_timer(dev, t, delay);
+	struct sk_buff		*skb;
+	struct skb_data		*entry;
+
+	while ((skb = skb_dequeue (&dev->done))) {
+		entry = (struct skb_data *) skb->cb;
+		switch (entry->state) {
+		case rx_done:
+			if (rx_process(dev, skb))
+				usb_free_skb(skb);
+			continue;
+		case tx_done:
+			kfree(entry->urb->sg);
+			fallthrough;
+		case rx_cleanup:
+			usb_free_skb(skb);
+			continue;
+		default:
+			netdev_dbg(dev->net, "bogus skb state %d\n", entry->state);
+		}
+	}
+
+	/* restart RX again after disabling due to high error rate */
+	clear_bit(EVENT_RX_KILL, &dev->flags);
+
+	/* waiting for all pending urbs to complete?
+	 * only then can we forgo submitting anew
+	 */
+	if (waitqueue_active(&dev->wait)) {
+		if (dev->txq.qlen + dev->rxq.qlen + dev->done.qlen == 0)
+			wake_up_all(&dev->wait);
+
+	// or are we maybe short a few urbs?
+	} else if (netif_running (dev->net) &&
+		   netif_device_present (dev->net) &&
+		   netif_carrier_ok(dev->net) &&
+		   !timer_pending(&dev->delay) &&
+		   !test_bit(EVENT_RX_PAUSED, &dev->flags) &&
+		   !test_bit(EVENT_RX_HALT, &dev->flags)) {
+		int	temp = dev->rxq.qlen;
+
+		if (temp < RX_QLEN(dev)) {
+			if (rx_alloc_submit(dev, GFP_ATOMIC) == -ENOLINK)
+				return;
+			if (temp != dev->rxq.qlen)
+				netif_dbg(dev, link, dev->net,
+					  "rxqlen %d --> %d\n",
+					  temp, dev->rxq.qlen);
+			if (dev->rxq.qlen < RX_QLEN(dev))
+				tasklet_schedule (&dev->bh);
+		}
+		if (dev->txq.qlen < TX_QLEN (dev))
+			netif_wake_queue (dev->net);
+	}
+}
+
+static void usbnet_bh_tasklet(struct tasklet_struct *t)
+{
+	struct usbnet *dev = from_tasklet(dev, t, bh);
+
+	usbnet_bh(&dev->delay);
+}
+
+
+/*-------------------------------------------------------------------------
+ *
+ * USB Device Driver support
+ *
+ *-------------------------------------------------------------------------*/
+
+// precondition: never called in_interrupt
+
+void usbnet_disconnect (struct usb_interface *intf)
+{
+	struct usbnet		*dev;
+	struct usb_device	*xdev;
+	struct net_device	*net;
+	struct urb		*urb;
+
+	dev = usb_get_intfdata(intf);
+	usb_set_intfdata(intf, NULL);
+	if (!dev)
+		return;
+
+	xdev = interface_to_usbdev (intf);
+
+	netif_info(dev, probe, dev->net, "unregister '%s' usb-%s-%s, %s\n",
+		   intf->dev.driver->name,
+		   xdev->bus->bus_name, xdev->devpath,
+		   dev->driver_info->description);
+
+	net = dev->net;
+	unregister_netdev (net);
+
+	while ((urb = usb_get_from_anchor(&dev->deferred))) {
+		dev_kfree_skb(urb->context);
+		kfree(urb->sg);
+		usb_free_urb(urb);
+	}
+
+	if (dev->driver_info->unbind)
+		dev->driver_info->unbind(dev, intf);
+
+	usb_kill_urb(dev->interrupt);
+	usb_free_urb(dev->interrupt);
+	kfree(dev->padding_pkt);
+
+	free_percpu(net->tstats);
+	free_netdev(net);
+}
+EXPORT_SYMBOL_GPL(usbnet_disconnect);
+
+static const struct net_device_ops usbnet_netdev_ops = {
+	.ndo_open		= usbnet_open,
+	.ndo_stop		= usbnet_stop,
+	.ndo_start_xmit		= usbnet_start_xmit,
+	.ndo_tx_timeout		= usbnet_tx_timeout,
+	.ndo_set_rx_mode	= usbnet_set_rx_mode,
+	.ndo_change_mtu		= usbnet_change_mtu,
+	.ndo_get_stats64	= dev_get_tstats64,
+	.ndo_set_mac_address 	= eth_mac_addr,
+	.ndo_validate_addr	= eth_validate_addr,
+};
+
+/*-------------------------------------------------------------------------*/
+
+// precondition: never called in_interrupt
+
+static struct device_type wlan_type = {
+	.name	= "wlan",
+};
+
+static struct device_type wwan_type = {
+	.name	= "wwan",
+};
+
+int
+usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
+{
+	struct usbnet			*dev;
+	struct net_device		*net;
+	struct usb_host_interface	*interface;
+	const struct driver_info	*info;
+	struct usb_device		*xdev;
+	int				status;
+	const char			*name;
+	struct usb_driver 	*driver = to_usb_driver(udev->dev.driver);
+
+	/* usbnet already took usb runtime pm, so have to enable the feature
+	 * for usb interface, otherwise usb_autopm_get_interface may return
+	 * failure if RUNTIME_PM is enabled.
+	 */
+	if (!driver->supports_autosuspend) {
+		driver->supports_autosuspend = 1;
+		pm_runtime_enable(&udev->dev);
+	}
+
+	name = udev->dev.driver->name;
+	info = (const struct driver_info *) prod->driver_info;
+	if (!info) {
+		dev_dbg (&udev->dev, "blacklisted by %s\n", name);
+		return -ENODEV;
+	}
+	xdev = interface_to_usbdev (udev);
+	interface = udev->cur_altsetting;
+
+	status = -ENOMEM;
+
+	// set up our own records
+	net = alloc_etherdev(sizeof(*dev));
+	if (!net)
+		goto out;
+
+	/* netdev_printk() needs this so do it as early as possible */
+	SET_NETDEV_DEV(net, &udev->dev);
+
+	dev = netdev_priv(net);
+	dev->udev = xdev;
+	dev->intf = udev;
+	dev->driver_info = info;
+	dev->driver_name = name;
+	dev->rx_speed = SPEED_UNSET;
+	dev->tx_speed = SPEED_UNSET;
+
+	net->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
+	if (!net->tstats)
+		goto out0;
+
+	dev->msg_enable = netif_msg_init (msg_level, NETIF_MSG_DRV
+				| NETIF_MSG_PROBE | NETIF_MSG_LINK);
+	init_waitqueue_head(&dev->wait);
+	skb_queue_head_init (&dev->rxq);
+	skb_queue_head_init (&dev->txq);
+	skb_queue_head_init (&dev->done);
+	skb_queue_head_init(&dev->rxq_pause);
+	tasklet_setup(&dev->bh, usbnet_bh_tasklet);
+	INIT_WORK (&dev->kevent, usbnet_deferred_kevent);
+	init_usb_anchor(&dev->deferred);
+	timer_setup(&dev->delay, usbnet_bh, 0);
+	mutex_init (&dev->phy_mutex);
+	mutex_init(&dev->interrupt_mutex);
+	dev->interrupt_count = 0;
+
+	dev->net = net;
+	strscpy(net->name, "usb%d", sizeof(net->name));
+	eth_hw_addr_set(net, node_id);
+
+	/* rx and tx sides can use different message sizes;
+	 * bind() should set rx_urb_size in that case.
+	 */
+	dev->hard_mtu = net->mtu + net->hard_header_len;
+	net->min_mtu = 0;
+	net->max_mtu = ETH_MAX_MTU;
+
+	net->netdev_ops = &usbnet_netdev_ops;
+	net->watchdog_timeo = TX_TIMEOUT_JIFFIES;
+	net->ethtool_ops = &usbnet_ethtool_ops;
+
+	// allow device-specific bind/init procedures
+	// NOTE net->name still not usable ...
+	if (info->bind) {
+		status = info->bind (dev, udev);
+		if (status < 0)
+			goto out1;
+
+		// heuristic:  "usb%d" for links we know are two-host,
+		// else "eth%d" when there's reasonable doubt.  userspace
+		// can rename the link if it knows better.
+		if ((dev->driver_info->flags & FLAG_ETHER) != 0 &&
+		    ((dev->driver_info->flags & FLAG_POINTTOPOINT) == 0 ||
+		     (net->dev_addr [0] & 0x02) == 0))
+			strscpy(net->name, "eth%d", sizeof(net->name));
+		/* WLAN devices should always be named "wlan%d" */
+		if ((dev->driver_info->flags & FLAG_WLAN) != 0)
+			strscpy(net->name, "wlan%d", sizeof(net->name));
+		/* WWAN devices should always be named "wwan%d" */
+		if ((dev->driver_info->flags & FLAG_WWAN) != 0)
+			strscpy(net->name, "wwan%d", sizeof(net->name));
+
+		/* devices that cannot do ARP */
+		if ((dev->driver_info->flags & FLAG_NOARP) != 0)
+			net->flags |= IFF_NOARP;
+
+		/* maybe the remote can't receive an Ethernet MTU */
+		if (net->mtu > (dev->hard_mtu - net->hard_header_len))
+			net->mtu = dev->hard_mtu - net->hard_header_len;
+	} else if (!info->in || !info->out)
+		status = usbnet_get_endpoints (dev, udev);
+	else {
+		u8 ep_addrs[3] = {
+			info->in + USB_DIR_IN, info->out + USB_DIR_OUT, 0
+		};
+
+		dev->in = usb_rcvbulkpipe (xdev, info->in);
+		dev->out = usb_sndbulkpipe (xdev, info->out);
+		if (!(info->flags & FLAG_NO_SETINT))
+			status = usb_set_interface (xdev,
+				interface->desc.bInterfaceNumber,
+				interface->desc.bAlternateSetting);
+		else
+			status = 0;
+
+		if (status == 0 && !usb_check_bulk_endpoints(udev, ep_addrs))
+			status = -EINVAL;
+	}
+	if (status >= 0 && dev->status)
+		status = init_status (dev, udev);
+	if (status < 0)
+		goto out3;
+
+	if (!dev->rx_urb_size)
+		dev->rx_urb_size = dev->hard_mtu;
+	dev->maxpacket = usb_maxpacket(dev->udev, dev->out);
+	if (dev->maxpacket == 0) {
+		/* that is a broken device */
+		status = -ENODEV;
+		goto out4;
+	}
+
+	/* let userspace know we have a random address */
+	if (ether_addr_equal(net->dev_addr, node_id))
+		net->addr_assign_type = NET_ADDR_RANDOM;
+
+	if ((dev->driver_info->flags & FLAG_WLAN) != 0)
+		SET_NETDEV_DEVTYPE(net, &wlan_type);
+	if ((dev->driver_info->flags & FLAG_WWAN) != 0)
+		SET_NETDEV_DEVTYPE(net, &wwan_type);
+
+	/* initialize max rx_qlen and tx_qlen */
+	usbnet_update_max_qlen(dev);
+
+	if (dev->can_dma_sg && !(info->flags & FLAG_SEND_ZLP) &&
+		!(info->flags & FLAG_MULTI_PACKET)) {
+		dev->padding_pkt = kzalloc(1, GFP_KERNEL);
+		if (!dev->padding_pkt) {
+			status = -ENOMEM;
+			goto out4;
+		}
+	}
+
+	status = register_netdev (net);
+	if (status)
+		goto out5;
+	netif_info(dev, probe, dev->net,
+		   "register '%s' at usb-%s-%s, %s, %pM\n",
+		   udev->dev.driver->name,
+		   xdev->bus->bus_name, xdev->devpath,
+		   dev->driver_info->description,
+		   net->dev_addr);
+
+	// ok, it's ready to go.
+	usb_set_intfdata (udev, dev);
+
+	netif_device_attach (net);
+
+	if (dev->driver_info->flags & FLAG_LINK_INTR)
+		usbnet_link_change(dev, 0, 0);
+
+	return 0;
+
+out5:
+	kfree(dev->padding_pkt);
+out4:
+	usb_free_urb(dev->interrupt);
+out3:
+	if (info->unbind)
+		info->unbind (dev, udev);
+out1:
+	/* subdrivers must undo all they did in bind() if they
+	 * fail it, but we may fail later and a deferred kevent
+	 * may trigger an error resubmitting itself and, worse,
+	 * schedule a timer. So we kill it all just in case.
+	 */
+	cancel_work_sync(&dev->kevent);
+	del_timer_sync(&dev->delay);
+	free_percpu(net->tstats);
+out0:
+	free_netdev(net);
+out:
+	return status;
+}
+EXPORT_SYMBOL_GPL(usbnet_probe);
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * suspend the whole driver as soon as the first interface is suspended
+ * resume only when the last interface is resumed
+ */
+
+int usbnet_suspend (struct usb_interface *intf, pm_message_t message)
+{
+	struct usbnet		*dev = usb_get_intfdata(intf);
+
+	if (!dev->suspend_count++) {
+		spin_lock_irq(&dev->txq.lock);
+		/* don't autosuspend while transmitting */
+		if (dev->txq.qlen && PMSG_IS_AUTO(message)) {
+			dev->suspend_count--;
+			spin_unlock_irq(&dev->txq.lock);
+			return -EBUSY;
+		} else {
+			set_bit(EVENT_DEV_ASLEEP, &dev->flags);
+			spin_unlock_irq(&dev->txq.lock);
+		}
+		/*
+		 * accelerate emptying of the rx and queues, to avoid
+		 * having everything error out.
+		 */
+		netif_device_detach (dev->net);
+		usbnet_terminate_urbs(dev);
+		__usbnet_status_stop_force(dev);
+
+		/*
+		 * reattach so runtime management can use and
+		 * wake the device
+		 */
+		netif_device_attach (dev->net);
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usbnet_suspend);
+
+int usbnet_resume (struct usb_interface *intf)
+{
+	struct usbnet		*dev = usb_get_intfdata(intf);
+	struct sk_buff          *skb;
+	struct urb              *res;
+	int                     retval;
+
+	if (!--dev->suspend_count) {
+		/* resume interrupt URB if it was previously submitted */
+		__usbnet_status_start_force(dev, GFP_NOIO);
+
+		spin_lock_irq(&dev->txq.lock);
+		while ((res = usb_get_from_anchor(&dev->deferred))) {
+
+			skb = (struct sk_buff *)res->context;
+			retval = usb_submit_urb(res, GFP_ATOMIC);
+			if (retval < 0) {
+				dev_kfree_skb_any(skb);
+				kfree(res->sg);
+				usb_free_urb(res);
+				usb_autopm_put_interface_async(dev->intf);
+			} else {
+				netif_trans_update(dev->net);
+				__skb_queue_tail(&dev->txq, skb);
+			}
+		}
+
+		smp_mb();
+		clear_bit(EVENT_DEV_ASLEEP, &dev->flags);
+		spin_unlock_irq(&dev->txq.lock);
+
+		if (test_bit(EVENT_DEV_OPEN, &dev->flags)) {
+			/* handle remote wakeup ASAP
+			 * we cannot race against stop
+			 */
+			if (netif_device_present(dev->net) &&
+				!timer_pending(&dev->delay) &&
+				!test_bit(EVENT_RX_HALT, &dev->flags))
+					rx_alloc_submit(dev, GFP_NOIO);
+
+			if (!(dev->txq.qlen >= TX_QLEN(dev)))
+				netif_tx_wake_all_queues(dev->net);
+			tasklet_schedule (&dev->bh);
+		}
+	}
+
+	if (test_and_clear_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags))
+		usb_autopm_get_interface_no_resume(intf);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usbnet_resume);
+
+/*
+ * Either a subdriver implements manage_power, then it is assumed to always
+ * be ready to be suspended or it reports the readiness to be suspended
+ * explicitly
+ */
+void usbnet_device_suggests_idle(struct usbnet *dev)
+{
+	if (!test_and_set_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags)) {
+		dev->intf->needs_remote_wakeup = 1;
+		usb_autopm_put_interface_async(dev->intf);
+	}
+}
+EXPORT_SYMBOL(usbnet_device_suggests_idle);
+
+/*
+ * For devices that can do without special commands
+ */
+int usbnet_manage_power(struct usbnet *dev, int on)
+{
+	dev->intf->needs_remote_wakeup = on;
+	return 0;
+}
+EXPORT_SYMBOL(usbnet_manage_power);
+
+void usbnet_link_change(struct usbnet *dev, bool link, bool need_reset)
+{
+	/* update link after link is reseted */
+	if (link && !need_reset)
+		netif_carrier_on(dev->net);
+	else
+		netif_carrier_off(dev->net);
+
+	if (need_reset && link)
+		usbnet_defer_kevent(dev, EVENT_LINK_RESET);
+	else
+		usbnet_defer_kevent(dev, EVENT_LINK_CHANGE);
+}
+EXPORT_SYMBOL(usbnet_link_change);
+
+/*-------------------------------------------------------------------------*/
+static int __usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
+			     u16 value, u16 index, void *data, u16 size)
+{
+	void *buf = NULL;
+	int err = -ENOMEM;
+
+	netdev_dbg(dev->net, "usbnet_read_cmd cmd=0x%02x reqtype=%02x"
+		   " value=0x%04x index=0x%04x size=%d\n",
+		   cmd, reqtype, value, index, size);
+
+	if (size) {
+		buf = kmalloc(size, GFP_NOIO);
+		if (!buf)
+			goto out;
+	}
+
+	err = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
+			      cmd, reqtype, value, index, buf, size,
+			      USB_CTRL_GET_TIMEOUT);
+	if (err > 0 && err <= size) {
+		if (data)
+			memcpy(data, buf, err);
+		else
+			netdev_dbg(dev->net,
+				   "Huh? Data requested but thrown away.\n");
+	}
+	kfree(buf);
+out:
+	return err;
+}
+
+static int __usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
+			      u16 value, u16 index, const void *data,
+			      u16 size)
+{
+	void *buf = NULL;
+	int err = -ENOMEM;
+
+	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
+		   " value=0x%04x index=0x%04x size=%d\n",
+		   cmd, reqtype, value, index, size);
+
+	if (data) {
+		buf = kmemdup(data, size, GFP_NOIO);
+		if (!buf)
+			goto out;
+	} else {
+        if (size) {
+            WARN_ON_ONCE(1);
+            err = -EINVAL;
+            goto out;
+        }
+    }
+
+	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
+			      cmd, reqtype, value, index, buf, size,
+			      USB_CTRL_SET_TIMEOUT);
+	kfree(buf);
+
+out:
+	return err;
+}
+
+/*
+ * The function can't be called inside suspend/resume callback,
+ * otherwise deadlock will be caused.
+ */
+int usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
+		    u16 value, u16 index, void *data, u16 size)
+{
+	int ret;
+
+	if (usb_autopm_get_interface(dev->intf) < 0)
+		return -ENODEV;
+	ret = __usbnet_read_cmd(dev, cmd, reqtype, value, index,
+				data, size);
+	usb_autopm_put_interface(dev->intf);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usbnet_read_cmd);
+
+/*
+ * The function can't be called inside suspend/resume callback,
+ * otherwise deadlock will be caused.
+ */
+int usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
+		     u16 value, u16 index, const void *data, u16 size)
+{
+	int ret;
+
+	if (usb_autopm_get_interface(dev->intf) < 0)
+		return -ENODEV;
+	ret = __usbnet_write_cmd(dev, cmd, reqtype, value, index,
+				 data, size);
+	usb_autopm_put_interface(dev->intf);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usbnet_write_cmd);
+
+/*
+ * The function can be called inside suspend/resume callback safely
+ * and should only be called by suspend/resume callback generally.
+ */
+int usbnet_read_cmd_nopm(struct usbnet *dev, u8 cmd, u8 reqtype,
+			  u16 value, u16 index, void *data, u16 size)
+{
+	return __usbnet_read_cmd(dev, cmd, reqtype, value, index,
+				 data, size);
+}
+EXPORT_SYMBOL_GPL(usbnet_read_cmd_nopm);
+
+/*
+ * The function can be called inside suspend/resume callback safely
+ * and should only be called by suspend/resume callback generally.
+ */
+int usbnet_write_cmd_nopm(struct usbnet *dev, u8 cmd, u8 reqtype,
+			  u16 value, u16 index, const void *data,
+			  u16 size)
+{
+	return __usbnet_write_cmd(dev, cmd, reqtype, value, index,
+				  data, size);
+}
+EXPORT_SYMBOL_GPL(usbnet_write_cmd_nopm);
+
+static void usbnet_async_cmd_cb(struct urb *urb)
+{
+	struct usb_ctrlrequest *req = (struct usb_ctrlrequest *)urb->context;
+	int status = urb->status;
+
+	if (status < 0)
+		dev_dbg(&urb->dev->dev, "%s failed with %d",
+			__func__, status);
+
+	kfree(req);
+	usb_free_urb(urb);
+}
+
+/*
+ * The caller must make sure that device can't be put into suspend
+ * state until the control URB completes.
+ */
+int usbnet_write_cmd_async(struct usbnet *dev, u8 cmd, u8 reqtype,
+			   u16 value, u16 index, const void *data, u16 size)
+{
+	struct usb_ctrlrequest *req;
+	struct urb *urb;
+	int err = -ENOMEM;
+	void *buf = NULL;
+
+	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
+		   " value=0x%04x index=0x%04x size=%d\n",
+		   cmd, reqtype, value, index, size);
+
+	urb = usb_alloc_urb(0, GFP_ATOMIC);
+	if (!urb)
+		goto fail;
+
+	if (data) {
+		buf = kmemdup(data, size, GFP_ATOMIC);
+		if (!buf) {
+			netdev_err(dev->net, "Error allocating buffer"
+				   " in %s!\n", __func__);
+			goto fail_free_urb;
+		}
+	}
+
+	req = kmalloc(sizeof(struct usb_ctrlrequest), GFP_ATOMIC);
+	if (!req)
+		goto fail_free_buf;
+
+	req->bRequestType = reqtype;
+	req->bRequest = cmd;
+	req->wValue = cpu_to_le16(value);
+	req->wIndex = cpu_to_le16(index);
+	req->wLength = cpu_to_le16(size);
+
+	usb_fill_control_urb(urb, dev->udev,
+			     usb_sndctrlpipe(dev->udev, 0),
+			     (void *)req, buf, size,
+			     usbnet_async_cmd_cb, req);
+	urb->transfer_flags |= URB_FREE_BUFFER;
+
+	err = usb_submit_urb(urb, GFP_ATOMIC);
+	if (err < 0) {
+		netdev_err(dev->net, "Error submitting the control"
+			   " message: status=%d\n", err);
+		goto fail_free_all;
+	}
+	return 0;
+
+fail_free_all:
+	kfree(req);
+fail_free_buf:
+	kfree(buf);
+	/*
+	 * avoid a double free
+	 * needed because the flag can be set only
+	 * after filling the URB
+	 */
+	urb->transfer_flags = 0;
+fail_free_urb:
+	usb_free_urb(urb);
+fail:
+	return err;
+
+}
+EXPORT_SYMBOL_GPL(usbnet_write_cmd_async);
+/*-------------------------------------------------------------------------*/
+
+static int __init usbnet_init(void)
+{
+	/* Compiler should optimize this out. */
+	BUILD_BUG_ON(
+		sizeof_field(struct sk_buff, cb) < sizeof(struct skb_data));
+
+	eth_random_addr(node_id);
+	return 0;
+}
+module_init(usbnet_init);
+
+static void __exit usbnet_exit(void)
+{
+}
+module_exit(usbnet_exit);
+
+MODULE_AUTHOR("David Brownell");
+MODULE_DESCRIPTION("USB network driver framework");
+MODULE_LICENSE("GPL");